| Acrylic acid series superabsorbents are easy prepared with cheap materials, but they are easy aged, and also possess poor moisture-proof ability. In this thesis, we prepared superabsorbents with high weather resisting property and high absorbency. The thesis includes the following aspects:Superabsorbents were synthesized by copolymerization of acrylic acid and hydroxyethylmethacrylate (HEMA), the absorbency and the weather resisting property of the prepared superabsorbents were also investigated. The results shows that the superabsorbents synthesized at 65～75℃with K2S2O8 as initiator, whose dosage was 0.04～0.06％, 80％of the neutralization degree of acrylic acid, and 4 hours of the reaction time, have higher absorbency; when the neutralization degree of acrylic acid, the temperature, the reaction time, the monomers concentration, the dosage of crosslinker and the level of HEMA increased, the weather resisting property of the prepared superabsorbents enhanced.The effect of surface modification and inner modification of superabsorbents by humic acid was studied; the results show that humic acid graft modification can improve the salt resisting ability of the superabsorbents. The superabsorbents modified by 7.5％humic acid have highest absorbency. The layered film has been observed on the surface of the humic acid surface modified superabsorbents, the water-absorption rate and the moisture-proof ability of which is obviously improved, while the effectiveness of inner graft modification is relatively small.The agricultural application of superabsorbents was investigated and the result shows that it can affect the emergence of seeding of crops and the temperature of the soil; it can increase the dilatability of the soil, reduce evaporation and change the water characteristic curves; it can increase the valid water and the temperature of the soil; it shows predominant effectiveness in promote the emergence of crop seeding. The survival ratio of tomato greatly increased from 37.5％, which was the survival ratio of the blank, to 83.3％, and the soil temperature around the network of roots was 2～4℃higher than the blank after the addition of superabsorbents.Using Grape and Chinese date trees as the test plants in Hami, Xinjiang, one of the most arid area in China, the effect of application level, application process of water retaining agent(WRA) on survival ratio, sugar content of the fruit, water content of soil of the fruited trees as well as the new transplanted trees was investigated. The Economic benefits of WRA application was also analyzed in this thesis. The results show that effectiveness of mixing dry WRA with soil was better than that of mixing gel fully absorbed water with soil. Application of SAP could obviously enhance the water holding capacity of the soil; the soil contains SAP hold more than double water content of the blank under severe drought condition. For new transplanted trees, 10g～30g per plant was the suitable level, which could increased survival ratio of transplanting by 20％and promote the tip growth; while for bearing-grape tree, 100g～200g per plant was the suitable level. When the application level was 100g and 200g per plant, rape yield increased by 12.59％and 25.29％respectively; sugar content increased by 9.92％and 6.01％respectively; the profit increased 664.5RMB and 1107RMB per 667m2 respectively. However, when the application level was 100g and 200g per plant at fruit-swelling stage under drought stress with 75％of normal irrigation rate, rape yield increased by 38.46％and 66.62％, respectively; sugar content increased by 0.78％; the profit increased 829.5RMB and 1437RMB per 667m2, respectively. |
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